Magnetic dewatering and concentrating means for magnetic separators



June 10, 1947.

H. K. MARTIN IAGNBTIC DEWATERING AND CONCENTRATING BANS FOR IAGNBTIC SEPARATORS Filed Oct. 22, "1943 INVENNR. HEN/Pr K Mam-1N firm/avers Patented June 10, 1947 UNITED STATES, PATENT OFFICE MAGNETIC DEWATERING AND CONCEN- TRATING MEANS FOR MAGNETIC SEPA- RATOBS Henry K. Martin, Ironwood, Mich., assignor to Reserve Mining Company, Babbit, Minn, a corporation of Minnesota Application October 22, 1943, Serial No. 507,268

(Cl. 209-232) I 6 Claims.

1 t The present invention relates to apparatus for separating mixed magnetic and non-magnetic .materials from each other, and more particularly netic and non-magnetic material and a better dewatering of the ore concentrates.

The invention resides in certain constructions and combinations and arrangements of parts and further objects and advantages thereof will be apparent to those skilled in the art to which it relates from the following description of the preferred embodiment described with reference to the accompanying drawings forming a part of this specification in which similar reference characters designate corresponding parts, and in arator for separating magnetic ore concentrates and middiings from eachother and/or from tailings and for dewatering the ore concentrates, wherein the material to be separated is caused to move under water in close proximity to the underside of an electric magnet but separated therefrom by a non-magnetic member and which includes magnet means located above the water and adjacent to the discharge end of the separator and below and spaced from the non-magnetic member for producing a high intensity magnetic field through'which the material carried by the non-magnetic member must pass, whereby said material is temporarily retarded and/0r diverted from the path which-it would otherwise normally take, thereby effecting a better separation of the magnetic and non-magnetic material and a drier ore concentrate.

A further specific object of the invention is the provision of a novel and improved magnetic separator for separating under water magnetic ore concentrates and middling's from each other and/or from tailings and for. dewaterlng the ore concentrates, wherein the material to be separated is caused to move under water in close proximity to the underside of a series of electric magnets but separated therefrom by a non-magnetic member and including means located adjacent to the discharge end of the separator above the water therein but below and spaced from the non-magnetic member for producing a magnet below said member having a high intensity magnetic held through which the material carried by the non-magnetic member must pass, whereby said material is temporarily diverted from the path which it would otherwise normally take, thereby effecting a better separation of the magwhich Fig. 1' is a longitudinal vertical section through a magnetic separator embodying the present invention; and

Fig. 2 is a section approximately on the line 2-2 of Fig. 1.

Referring to the drawings, the particular magnetic separator shown therein is of the general type shown in United States Patents to Robert E. Crockett, Nos. 2,003,430 and 2,090,112 and will not be herein described in detail. Suflice it to say that the separator shown comprises an irregularly-shaped tank'or reservoir, designated generally by the reference character A, supported by a frame B, which frame also supports the magnet assembly 0 and the drums l0 'and II which carry the endless conveyor l2. As shown, the tank A comprises a hopper If! for receiving the tailings, a hopper I 4 for receiving the middiings and a hopper ii for receiving the ore concentrates in addition to the right-hand portion l6 where the material to be separated is fed to the separator and in turn to the conveyor H.

The magnet assembly 0 comprises a plurality of magnets I'I having pole 'pieces 18 disposed closely adjacent to the upper side of the lower reach of the endless conveyor H, which conveyor is made cinch-magnetic material. Alternate pole pieces it are of difl'erent polarity and iorm a magnetic field having successive sections of opposite polarity through which the lower reach of the conveyor travels. The magnetic field produced by the magnets I1 extends substantially the entire length of the lower reach, of the conveyor H. In operation, water is maintained in the tank A up to about the level shown in the drawings and indicated by the reference character 20. The drums l0 and H which carry the endless conveyor I2 are keyed to shafts II and 22 located adjacent to opposite ends of the separator and rotatably supported in bushings 23 and 24, respectively, fixed to the channel irons 25 forming part of the frame B. Either or both of the shafts 2| and 22 may be driven as desired.

The lower reach of the conveyor I2 and the magnetic field produced by the magnet assembly C are substantially catenary in shape and the discharge end of the conveyor is located, above the level of the water in the reservoir A with at least the intermediate section of the lower reach of the conveyor located below the level of the water. The entrance end of the conveyor I2 maybe above or below the level of the water in the reservoir A as desired. 1'

The magnetic and non-magnetic material to be separated is fed to the entrance or right-hand end I6 of the separator in any convenient mannet as by a hopper 26 and is carried by water admitted along with the material through the hopper 26 and/or by separate means, such as th pipe 21, to a point underneath the righthand end of the lower reach of the conveyor I2 and into the magnetic field produced by the magnets I'I. The magnetic particles ar carried along by the conveyor I2 while the tailings drop intothe hopper I3. The middlings which are composed of both magnetic and non-magnetic material arecarried along by the conveyor I2 to a point abov the hopper I4.

' According to the provisions of the present invention, a strong magnetic field is produced by means located underneath and spaced from the lower reach of the conveyor or belt I2 through which magnetic fieldmaterial carried on the conveyor passes after it leaves the water. This magnetic field temporarily retards the travel of the conveyor I2 advances'past the pole pieces I8, the alternate polarity thereof will cause a constant rearrangement of the magnetic particles thus releasing some of the mechanically included, non-magneticmaterial, and also some individually very small in size) will be clingingto the underside o the conveyor I2 in chains or threads in the same manner as iron filings cling to the poles of a magnet. Hence, the water between adjacent chains or threads of the magnetic particles will immediately run off. 'However, considerable water and non-magnetic particles will be occluded in the lengths of the chains or threads of the particles and it is this water and non-magnetic material, as well as that between the chains or threads, which my improved apparatus efl'ectively releases to produce a concentrate which is much drier and purer than that delivered by prior devices.

This improved dewatering and concentration, in the illustrated embodiment, results from the provision of the permeable bar 38 and the nonand rearranges the particles of material adhering to the conveyor I2 and causes some or all of them to temporarily leave the conveyor as they pass therethrough. As shown, a bar or member of magnetic material is located underneath the lower reach of the conveyor I2 and v spaced therefrom a short distance, thus form-.

ing a slot or aperture 3| through which material carried along by the conveyor must pass. Preferably the bar 30' is located intermediate adjoining poles I8 of the magnets l1 and being magnetized due to its location in the magnetic field formed by the magnets I'I cooperates therewith to produce a magnet underneath the conveyor I2, the poles of which magnet form high intensity magnetic fields at opposite sides of the bar through which fields the material adhering to the conveyor must pass. As the material carried along by th conveyor I2 enters the strong magnetic field adjacent to and produced by the bar 30 it tends to follow the path of greatest magnetism and part of it is attracted towards or to the bar. At the opposite side of the bar the magnetic material attracted away from the conveyor by the bar 30 again returns to the conveyor. A non-magnetic shield 32 located immediately above the bar 38 and extendinga-considerable distance on either side thereof prevents magnetic material from permanently adhering to the bar.

As previously mentioned, and more fully described in the Crockett Patent No. 2,090,112, the material to be separated is fed against the lower surface 'of the moving conveyor I2 at the righthand end thereof (Fig. 1), whereupon the magnets I'I continuously attract and hold the magnetic material to the conveyor so that a. continuous mat or strip of material is formed on the lower side of the conveyor and moved through the separator. This mat or strip of material will include some non-magnetic material which is mechanically held to the conveyor by the irregular shape of magnetic particles. However, as

magnetic shield 32 adjacent the pole pieces I8.

, The bar 30 being within the magnetic field produced by the-magnets Il, becomes-an induced magnet and strengthens the magnetic field at that point. If the bar is directly below one of the pole pieces I8 of the magnets H, the top of the said bar will have a pole of opposite polarity to that of the pol piece I8 thereabove. If

the bar 30"be below and intermediate two of the pole pieces I8, there will be two magnetic poles induced in the top surface of the bar 30,

one adjacent each side thereof, and each of opposit polarity relative to the adjacent poles I8. The action of the bar 30 is, therefore, substantially the same whether the said bar be located exactly opposite a pole piece I8 or intermediate two such' pole pieces. In either case, as the material and water carried by the conveyor I2 reach th region of the bar 30, a portion of the magnetic material leaves the conveyor and adheres to the shield 32 above the bar. This results from the fact that the lower ends of the chains 01' threads of particles carried on the conveyor I2 will be closer to the bar 38 than to the pole pieces I8 of the magnets I'I so that the former will have a greater influence on these lower particles than do the magnets IT. The magnetic particles so attracted to the shield 32 by the bar 30 will tend to build up thereon as a dam or dams (there being two dams if the bar be placed between two of the adjacent pole pieces). i

The dam or. dams so formed furtherrestrict the relatively narrow gap 3| (defined by the shield 32 and conveyor I2) "through which the material must pass with the result that the j threads or chains of magnetic particles are both mechanically and magnetically disrupted-thus freeing the occluded water and non-magnetic particles which flow back to the hopper I4. Since the conveyor IZ is in continuous motion, the dewatered magnetic particles are carried away from the'region of the bar 38 and the shield 32 as new water-bearing material enters the region from the other side. The dam or" dams formed on the shield 32 are, therefore, constantly depleted and rebuilt as the material leaves and enters the region with said dam or dams being maintained at substantially the same size. Thus, if the dams become too high the magnets I! will have greater influence th'an bar 30 so that the upper particles are attracted to the conveyor l2. On the other hand, as the height of the dam or dams decrease, th magnetic effect of bar 30 upon the lower ones of the new particles brought into the region by the conveyor l2 will be sufficient to attract them to the shield 32 to replenish the said dam or dams. In the same manner, material is constantly being supplied to the righthand end of the shield 32 (as viewed in Fig. 1) and the previously supplied material is removed from the left-hand end of the shield.

It will be apparent, therefore, that the bar 30 not only strengthens the magnetic field so as to produce a closer grouping of the particles in the region thereof, but also creates a condition productive of a mechanical rearranging of the particles so that th resulting concentrate is both purer and drier than that resulting from simply increasing the magnetic field (i. e., by increasing the current in the energizing coils of magnets ll) without the use of the bar 30 and shield 32.

The bar 30 and shield 32 may be supported in any convenient manner, above the level of the water in the reservoir A and adjacent to the left or discharge end of the bottom of the catenary curve or shape taken by thelower reach of the conveyor i2. As shown, the bar 30 is fixed to the non-magnetic shield 32 which in turn is suspended from the magnet assembly C by the members 33 and 34 (see Fig. 2) and the shield 32 is constructed (as illustrated in Fig. 1) with a relatively fiat section extending parallel with the travel ofthe conveyor.

In the preferred embodiment of the invention shown, a single bar 30 is shown just above the level of the water in the reservoir A and above the hopper I4 and a similar assembly, designated generally by the reference character 35, located also above the water in the reservoir but closer to the discharge point of the conveyor. The device 35 is similar in construction and operation to the bar assembly comprising the bar 30 and the shield 32 except for the fact that it comprises two bars 36 and 31 similar to the bar 30 located underneath a single shield or member 38. If desired, either or both ends of the shields may be bent downward. In practice, the height of the aperture 3|, that-is the distance between adjacent surfaces of the shield and conveyor,

' will vary depending upon the size, etc., of the material being separated. Distances of from A," to have been used satisfactorily with ore concentrates.

As previously described in detail, the purpose of the magnetic bars shown is to produce, in cooperation with the magnets H, a magnet or magnets ora magnetic pole or poles underneath the conveyor creating a strong magnetic field or fields It is also to be understood that the means used to produce the strong magnetic field or fields can be located in any desired place along the lower reach of the conveyor l2 and that if bars and shields similarto those shown are usedany suitable arrangement thereof may be employed. Upon test the product of a separator similar to that shown in th drawings, having a single permeable bar and shield like the bar 30 and shield 32 shown, located approximately in the position of the bar assembly 35 and having a gap between the shield and the conveyor, contained 53.19% solids/of which 63.81% was iron, whereas the product of the same separator without the bar and shield assembly contained only 29.47% solids, of which only 62.44% was iron.

The preferred embodiment of the invention herein shown is merely illustrative of the invention and it is not to be considered as limited to the particular construction shown. The present invention can be applied to other types of separators and numerous changes can be made in the construction shown herein within the scope of the invention, as will be understood by those skilled in the art to which it relates, for example, the tank A may be of any desired shape and/or construction and may employ any known or desired baffle or hopper arrangement.

It will be apparent from the foregoing disclosure that the objects of the invention heretofore enumerated and others have been accomplished and that a new and improved magnetic separator especially adapted for separating ore concencrates and middlings from each other and/ or from tailings has been provided which separator will produce a purer and drier product than magnetic separators heretofore known and used in the iron ore industry and it is my intention to hereby cover all adaptations, modifications and uses of the invention herein disclosed which come within the practice of those skilled in the art to which it relates and the spirit and scope of the appended claims.

Having thus described my invention, what I claim is:

1. In a magnetic separator for separating magnetic and non-magnetic material such as ore concentrates and middlings from each other and/or from tailings, the combination of: a reservoir or tank; means for supplying liquid to said tank; a flexible non-magnetic conveyor having a portion submerged in the liquid in said tank and a portion thereof adjacent to the discharge end of the separator disposed above the surface of said liquid; means for moving said conveyor; a plurality of magnets having pole faces disposed closely adjacent to the upper side of parts of said submerged portion and said non-submerged portion of said conveyor for producing a continuous magnetic field on the opposite side of said conveyor; means for feeding material tc-be separated to said tank and causing it to come in close proximity to the underside of said conveyor in said magnetic field whereby said magnetic field causes magnetic ma-v terialin said mixture to =engageand be carried along by said conveyor; magnet means located below said non-submerged portion of said conveyor and opposite said pole faces for producing a high intensity magnetic field through which material being carried along by said conveyor must pass and within which the material will concentrate thus expediting the removal of the liquid; and a non-magnetic member or shield interposed between said conveyor and said mag net means.

2. In a magnetic separator for separating mag netic and non-magnetic material such as ore concentrates and middlings from each other and/or from tailings, the combination of: a reservoir or tank; means for supplying liquid to said tank; a flexible non-magnetic conveyor having a portion of substantially catenary shape a part of which is submerged in the liquid in said tank; said conveyor having a portion of the catenary-part thereof adjacent to the discharge end-of the conveyor disposed above the surface-of said liquid; means for moving said conveyor; a plurality of magnets having pole faces of alternate polaritydisposed closely adjacent to the upper side of parts of said submerged portion and said non-submerged portion of said conveyor for producing a continuous magnetic field having successive sections of opposite polarity on the opposite side of said conveyor; means for feeding material to be separated to said tank and causing'it to come in close proximity to the underside of said conveyor in said magnetic field whereby said magnetic field causes magnetic material in said mixture to be carried along by said conveyor; and magnet means located below said conveyor adjacent to the discharge end thereof and above the surface of the liquid in said tank and cooperating with said pole faces for producing'a high intensity magnetic field adjacent thereto through which material carried along by said conveyor must pass and within which the material will concentrate thus expediting the removal of the liquid; said means including a nonmagnetic member or shield adjacent to but spaced from said conveyor.

3. In a magnetic separator for separating magnetic and non-magnetic material such as ore concentrates and middlings from each other and/or from tailings, the combination of: a reservoir or tank; means for supplying liquid to said tank; a flexible non-magnetic conveyor having a portion of substantially catenary shape a part of whichis submerged in the liquid in said tank; said conveyor having a portion of the catenary part thereof adjacent to the discharge end of the conveyor disposed above the surface of said liquid; means for moving said conveyor; a plurality of magnets having pole faces disposed closely adjacent to the upper side of parts of said submerged portion and said non-submerged portion of said conveyor for producing a continuous magnetic field on the opposite side of said conveyor; means for feeding material to be separated to said tank and causing it to come in close proximity to the underside of said conveyor in said magnetic field whereby said magnetic field causes magneticymaterial in said mixture to engage and be carried along by said conveyor; a member formed of permeable material located above the surface of the liquid in said reservoir and below said conveyor adjacent to the discharge end thereof and intermediate two of said pole faces and cooperating with said pole faces for producing a high intensity magnetic field through which material carried along by said conveyor must pass; and a non-magnetic member or shield located above said last-named member.

4. In a magnetic separator for separating magnetic and non-magnetic material such as ore concentrates and middlings from each other and/or from tailings, the combination of: a reservoir tank; means for supplying liquid to said tank; a flexible non-magnetic conveyor having a portion of substantially catenary shape a part of which is submerged in the liquid in said tank; said conveyor having a portion of the catenary part thereof adjacent to the discharge end of the conveyor disposed above the surface of said liquid; means for moving said conveyor; a plurality of magnets havin pole faces of alternate polarity disposed closely adjacent to the upper side of parts of said magnetic material in said mixture to engage and be carried along by said conveyor; a member formed of permeable material'located intermediate two of said pole faces and below said conveyor adjacent to the discharge end thereof and above the surface of the liquid in said tank and cooperating with said pole faces for producing a high intensity magnetic field along opposite sides of said member; and a member or shield interposed between said conveyor and said last-named member and forming with said conveyor an aperture through which material carried along by said conveyor must pass.

5. In a magnetic separator for separating magnetic and non-magnetic material such as ore concentrates and middlings from each other and/or from tailings, the combination of: a reservoir or tank; means for supplying liquid to said tank; two horizontally spaced rollers or drums; a flexible non-magnetic continuous conveyor or belt extending around said rollers and having a portion of the lower reach thereof submerged in the liquid in said tank and a portion of said reach adjacent one end disposed above the level of said liquid, said end constituting the discharge end for magnetic material or concentrates; means for causing said conveyor to travel about said rollers in such a direction that said lower reach travels towards said discharge end; a plurality of magnets having pole faces of alternate polarity disposed'closely adjacent to the upper side of a part of said portions of the lower reach of said COD? veyor both above and below the surface of said liquid for producing a continuous magnetic field having successive sections of opposite polarity on the opposite side of said conveyor; means for feeding material to be separated to said-tank and causing it to come in close proximity to the underside of said conveyor in said magnetic field whereby said magnetic field causes magnetic material in said mixture to be carried along by said conveyor; a bar of permeable material located inter- Y mediate two of said pole faces and above the water in said tank and below said conveyor adjacent to the discharge end and extending transversely thereof for producing a high intensity magnetic field through which the material .car-

ried along by said conveyor must pass; and anonbar but I magnetic shield above said permeable spaced from said conveyor.

6. In a magnetic separator for separating 'mag-' REFERENCES CITED The following references are of record in the 5 file of this patent:

UNITED STATES PATENTS Number Name Date Crockett June 4, 1935 Crockett Aug. 17, 1937 Manegold July 22, 1919 Linney Aug, 22, 1944 

